Cummins ISB 5.9L 24 Valve Engine Specs, Problems & Reliability

Cummins ISB 5.9L 24-Valve Engine

Here in this post, I have gathered information about the Cummins ISB 5.9L 24 Valve Engine from its official website, including its specifications, Problems, and Reliability.

We believe in providing reliable information to our readers, therefore we prefer to obtain information on the Cummins ISB 5.9L 24 Valve Engine from authentic sources.

This article, which has been updated, has all the information you require about the Cummins ISB 5.9L 24 Valve Engine.

Cummins ISB 5.9L 24-Valve Engine

The ISB 5.9L is a turbodiesel straight-six engine that belongs to the B series. In 1998, the 6BT 5.9L was superseded by the ISB engine.

The engine’s basic form was preserved, but it was upgraded with cutting-edge components to make it more potent, more efficient, and less harmful to the environment.

Cast iron is used for the engine block. It shares the 6BT’s bore size and piston stroke. The ISB’s pistons are made of aluminium and have a symmetrical combustion bowl, while the connecting rods are made of forged steel.

The camshaft is constructed. Inside the block is where you’ll find the camshaft. The ISB motor used a pushrod engine architecture with many valves.

It has a 24-valve cast iron cylinder head that stands out (but it still has an OHV valvetrain). Two valves are pushed by each rocker’s arm.

This change necessitated the installation of a Bosch VP44 electronic fuel injection pump, a rotary type, into the fuel delivery system of the ISB engines (Robert Bosch GmbH).

The 24V engine’s components could be accessed easily and quickly for maintenance thanks to its aluminium intake manifold and new, one-piece, red or silver aluminium valve cover.

Firing order 1-5-3-6-2-4
Engine oil weight SAE 15W40 diesel oil
Engine oil capacity, liter
12 qts (11.4 liters) with filter.
Oil change interval, mile
7,500 (12,000 km) or 6 month
Dodge Ram pickup trucks, buses, medium duty trucks, marines
Production years
Cylinder block material
Cast Iron
Cylinder head material
Cast Iron
Fuel type
Fuel system
1998-2002. Electronically controlled Bosch VP44 rotary injection pump.
2003-2009. Bosch high pre
Number of cylinders
Valves per cylinder
Valvetrain layout
Bore, mm
4.02 inch, 102 mm
Stroke, mm
4.72 inch, 119 mm
Displacement, cc
359 cubic inches, 5.9 liters
Type of internal combustion engine
Four-stroke, turbocharged
Compression Ratio
16.3:1; 17.2:1 HO version
Power, hp

Cylinder block

Cylinder block alloy Cast iron
Compression ratio: 17.2:1
Cylinder bore: 102.0 mm (4.02 in)
Piston stroke: 120.0 mm (4.72 in)
Number of piston rings (compression / oil): 2/1
Number of main bearings: 7
Cylinder bore inner diameter: 102.000-102.116 mm (4.0157-4.0203 in)
Piston skirt diameter 101.750-101.793 mm (4.0059-4.0076 in)
Piston ring end gap: First 0.260-0.360 mm (0.0102-0.0142 in)
Second 0.850-1.150 mm (0.0335-0.0453 in)
Oil 0.250-0.550 mm (0.0098-0.0217 in)
Piston pin outer diameter 339.990-40.003 mm (1.5744-1.5749 in)
Crankshaft main journal diameter: 82.962-83.013 mm (3.2662-3.2682 in)

Maintenance Data

Valve clearance (Cold)

Intake valve 0.25 mm (0.010 in)
Exhaust valve 0.50 mm (0.020 in)

Oil system

Recommended engine oil 10W-30 (CE or CE/SG)
Engine oil capacity With oil filter change: 11.4 L (12.05 US. qt, 10.03 Imp. qt.)

Cummins ISB 5.9L 24 Valve Engine Specs, Problems & Reliability

The ISB 5.9 diesel engine’s famed reputation as a tough, dependable, and potent workhorse remains untarnished.

Having an all-iron engine means it can last a long time and be rebuilt if necessary. Unlike the mechanical fuel pump operated by a camshaft gear in earlier B series engines, the electric fuel pump in ISB camshafts is driven by electricity and so is more reliable.

There is still evidence of the electronic system. However, the electronic VP44 pump has a higher rate of failure than the traditional mechanical P7100 injection pump.

It’s not cheap to correct Common Rail injection problems, and it’s more fuel-picky.

Cummins ISB 5.9L 24 Valve Engine Review 

Cummins ISB 5,9L 24 Valve is a turbocharged, 6-cylinder inline engine. It was manufactured from 1998 until 2007. The engine is known for reliability, durability, and high torque output. For a full review, please check this YouTube video Here.

Cummins ISB 5.9L 24 Valve Engine FAQ

How much horsepower does a 5.9 24-valve Cummins have?

The first generation of the 5.9-liter engine, equipped with 24 valves, generated 235 hp and 460 lb-ft of torque through a manual transmission.

Productivity dropped when using an automated (215 horsepower and 420 lb-ft of torque) machine.

What does 5.9 ISB mean?

One of the largest straight-six engines seen in light truck vehicles and school buses is the 5.9 L, 359.0 cu in (5,883 cc) ISB (Interact System B); the 2004 edition of its enhanced high output 600 variant was featured on Ward’s 10 Best Engines list.

How many miles will a 24 valve Cummins last?

How long a 24-valve Cummins diesel engine lasts depends on how well it is maintained. Consumer reports indicate an average lifespan of 300,000–500,000 miles. Still, there have been reports of 24-valve Cummins engine lifetimes in excess of 500,000 miles.

What is a ISB motor?

Cummins ISB engines are inline diesel engines with 4 or 6 cylinders that power commercial passenger cars. There is a 6.7-litre 6-cylinder engine and a 4.5-litre 4-cylinder engine available.

What years were the 24 valve Cummins made?

This is especially true for the 5.9L 24-valve Cummins engines produced between 1998 and 2002.

When Cummins upgraded from the 12-valve to the 24-valve in 1998.5, it also rebuilt the head, replaced the p-pump with a VP44 (electronically controlled), and made a few other tweaks.

Notify of

Inline Feedbacks
View all comments